In the manual or automatic application of paint to objects, a partial flow of the paint which generally contains both solid matter and/or binding agents as well as solvents, is not applied to the object. This partial flow in the industry is referred to as “overspray”. Furthermore, overspray is always understood in the context of a dispersed system such as an emulsion or a suspension, or a combination thereof. The overspray is acquired by the airflow in the painting booth and fed to a separator such that the air, optionally upon suitable conditioning, can be redirected into the coating booth.
In particular in the case of installations with a high consumption of paint, for example in the case of installations for painting vehicle bodies, wet depositing systems, on the one hand, or electrostatically operating dry depositing systems, on the other hand are used in a known manner. In the case of known wet separators, a comparatively large amount of energy is required for recirculating the rather large quantity of water required. The preparation of the rinsing water on account of the high-level of chemicals that bind and de-tack paint and on account of the disposal of the paint sludge is cost intensive. Furthermore, the air on account of the intensive contact with the rinsing water absorbs a large amount of moisture which in the recirculating operation in turn results in a high consumption of energy for the preparation of the air. In the case of electrostatically operating dry separators, the paint overspray has to be continuously removed from the depositing faces which is often associated with rather complex measures in terms of construction and can accordingly be prone to malfunctions. Moreover, the energy input in the case of such separators is comparatively high.
As an alternative to these depositing systems, devices of the type mentioned at the outset which operate using exchangeable filter modules which upon reaching a limit load with overspray are exchanged for unladen filter modules and are disposed of or optionally recycled are known. The preparation and/or disposal of filter modules of this type in terms of energy as well as in terms of the resources required can be more sustainable than the investment in the case of a wet separator or of an electrostatically operating depositing device.
Such filter modules are fed to the overspray-charged booth air which flows through the filter module and leaves the latter as exhaust air that is largely relieved of overspray. For the sake of simplicity, such an exhaust air hereunder is also referred to as booth air or as booth air that is relieved of overspray.